Musical instrument



Sept. 15, 1931. 5 sw so 1,822,941

MUSICAL INSTRUMENT Original Filed March 7. 1927 5 Sheets-Sheet l ATTUR/VZFS P 1931. s. A. SWANSON 1,822,941

MUSICAL INSTRUMENT I Original Filed March 7, 1927 5 Sheets-Sheet 2 ATTU/P/Vf/SI Sept. 15, 1931. s. A. SWANSON 1,822,941

MUSICAL INSTRUMENT Original Filed March 7, 1927 5 Sheets-Sheet 3 MB 5J3[5 11 DB fly. 5. 4

34 a g; u u u u uww E f ma s A 7 TUBA/[75.

s. A. SWANSON MUSICAL INSTRUMENT Sept. 15, 1931.

5 Sheets-Sheet 4 Original Filed March 7. 1927 17y ffl 35 Sept. 15, 1931.s, A sw so 1,822,941

MUSICAL INSTRUMENT Original Filed March 7. 1927 5 Sheets-Sheet 5 .II VM17 m MI, I '1' Patented Sept. 15, 1931 SELVIYOR A. SRVANSON, OFCHICAGO, ILLINOIS MUSICAL INSTRUMENT Application filed March '7, 1927,Serial No. 173,277. Renewed January 15, 1931.

novel and pleasing musical effects may be obtained while the instrumentis being operated in the usual manner.

A further object of the invention is to provide an improved musicalinstrument with which, while a selection is being played in the usualmanner, a series of notes of different timbre may be played which aremusically related to one series of notes of the selection.

A further object of this invention is to provide an improved musicalinstrument of the type which may be operated either manually orautomatically in the playing of a selection, and with which during suchplaying, the air of the selection may be addition ally playedautomatically and concomitantly by notes of different timbre from theregular selection.

A still further object of the invention is to provide improved means foroperating musical sound-producing devices in any selected or desiredsequence.

A further object is to provide an improved musical instrument havingmeans of standard construction for producing primary sound effects, andmeans for producing novel secondary sound effects, said latter meansbeing adapted to be incorporated with said former means substantiallywithout changing the construction or arrangement thereof.

Another object is to provide an improved musical instrument in which theabove secondary sound-producing means are so arranged that the primarysoundproducing means can be adjusted or removed from and inserted in theinstrument without the necessity of interfering with or disturbing'theadjustment of said secondary means.

A further object of the invention is to provide an improved musicalinstrument which w ill accomplish any of the foregoing objects, andwhich will be relatively simple, dependable, durable. compact andinexpensive.

Various other objects and advantages will be apparent from the followingdescription of an embodiment of the invention, and the novel featureswill be particularly pointed out hereinafter in connection with theappended claims.

In. the accompanying drawings Fig. l is a sectional elevation of part ofa player piano constructed in accordance with this invention;

Fig. 2 is another sectional elevation of the same, the section beingtaken approximately along the line 22 of Fig. 1;

Fig. 3 is a plan of the control box of the Fig. i a side elevation ofthe control box;

F 5 is a bottom view of the upper section of the control box, viewed asalong the line 5-5. Fig. l, and looking in the direction of the arrows;

6 is a plan of the lower section of the control box, viewed as in thedirection of the arrow 6 in Fig. 4;;

7 is a plan of a portion of Fig. 5 on a somewhat larger scale, and withcertain parts removed to show other parts;

Fig. Sis a sectional elevation of the control box, the section beingtaken approximately along the line 8-8 of Fig. 4;

Fi 9 is an elevation similar to Fig. 8, but with the parts in adifferent operative relation to one another;

10 is another sectional elevation of a po tion of the control box, thesection being taken approximately along the line 10-10 of Fig. 1.1 is asectional elevation of another art of the control box, the section beingen approximately along the line 11-11 F 8; and

Fig. 12 is a sectional elevation of still another part of the controlbox, the section being taken approximately along the line 12l2 of 4-.

In the illustrated embodiment of the invention, a player piano may serveas the primary musical instrument, which may be operated to pro wemusical notes, either by manual lation of any of the usual keys 10 ins.l and 2) mounted on the keyboard in the usual manner, or by the usualauton'latic p r mechanism. Each key is operable, at it. rear end, upon asuitable key action mechanism 11 for striking a hammer er bar 15, andconduits 16 connect different sections of the tracker bar with theprimary pneumatic devices 17. The primary pneumatic devices 17 may be ofany suitable con struction employed in player pianos, and thereforetheir details are not illustrated herein, since per se they form no partof this invention. In the particular example illustrated, a branchpassage 18 communicates with an upper individual chamber 19 of eachprimary pneumatic device, and the conduit 18, in turn, is connected to amain suction conduit 20 which is connected to a suction or vacuumcreating device 21 of any suitable or usual construction.

Through suitable valve mechanism 170; provided in each primary pneumaticdevice, each chamber 19 is connected to an individual pneumatic motor22, there being a pneumatic motor for each key and for each conduit 16.The pneumatic motor 22 will be operated through the valve mechanism 17 ain accordance with the openings of the tracker bar which are uncoveredby the moving player roll, as usual in player piano mechanism. Eachmotor 22 is connected, in any suitable manner, to operate the hammers12, and as an example of a connection for that purpose,

each motor 22 may be'provided with a finger 23, engageable with a link11a of the key action 11 for a corresponding key 10, so that the hammerswill be operated pneumatically in accordance with the openings in theplayer roll 14. Each finger 23 has a lost motion con:

. 'nection to its corresponding key action link 111;, so that each keybe operated manually without operating its related motor 22.

A main control box or element 24 is arranged in the piano at anysuitable point, and contains a plurality of chambers 25 (Figs. 5, 8, 9,10 and 11) which are disposed side by side, and communicate with oneanother successively by individual passages 26.

. A branch 27 (Fig. 1) of the suction pipe 20 is connected to a passage28 in one end of the control box 24, the connection being controlled bya suitable valve 29, such as a plate face of the box 24. 7

Thevalve 29 has an aperture 31, which, when the plate is pulledoutwardly, is shifted into alignment with the passage 28 and the pipebranch 27, so as to establish communisliding in a chamber 30, providedat the lower cation between the suction pipe20 and one of the endchambers 25 of the casing. The suction connection through the pipe 27will cause the creation of a partial vacuum in the first end chamber 25,and through the passages 26, this partial vacuum will in turn be createdsuccessively in successive cham ers 25.

The box or casing 24 is provided,ialong its upper face, with a pluralityof valve chambers or cavities 32, and each valve chamber communicateswith an adjacent main chamber 25 through a valve passage 33. '14panshaped valve ring 34 may be secured across the open end of each valvechamber 32, and each ofsuch rings has an aperture 35. A

bar 36 extends across the open face of each valve chamber 32 andslidingly supports one end of a valve rod 37, the other end of the valverod extending through the valve passage 33 and into a chamber 25, andthe inner end of each valve rod being slidingly supof the valve chamberover the passage 33 to close the same, and against the valve seat or'ring 34 to close the opening 35 therein. The distance between the ring34 and the bottom wall of each valve chamber is greater than thedistance between the valve disks 39 and 40, so that the valve rod andits'disks may reciprocate alternately between the positions shown inFigs. 8 and 9, and thus connect the valve chamber 32 either with theadjacent related chamber 25, as when the valve stem is in the positionshown in Fig. 9, or with the atmosphere through the opening 35 when thevalve stem is in the position shown in Fig. 8.

Each valve chamber .32 is connected by a conduit 41 with a suitablesecondary sound-' fer in timbre from those produced by the primarysound-producing instrumentalities,

and for example may have a timbre such as that of a violin, a flute, orother musical instrument ordevice. These secondary sound producingdevices are 7 preferably pneumatically controlled individually by theconduits 41. Inasmuch as pneumatically controlled or operatedsound-producingdevices are so ill) well known in. the art, the detailsof the same have been omitted in this application in the interest ofsimplicity and brevity, and it will be understood that sound-producingdevices other than those illustrated may be substituted within the scopeof the invention.

When any conduit 41 is connected to a main chamber 25 of the control boxor element 24, such as when the valve rod 37 in the chamber with whichthat conduit 41 communicates is raised or is in the position shown inFig. 9, the partial vacuum in that chamber 25 will be communicated tothe conduit 41 and cause an operation of that sound-producing device.When the valve rod 37 is returned to the normal position shown in Fig.8, the suction will be removed from the conduit 41, and the latter willbe vented through its valve chamber 32 and the opening 35 to break itsvacuum and therefore stop operation of that particular secondary soundproducing device.

Each passage 26, which connects two adjacent chambers 25, is controlledby a valve head 43 located in one of the chambers 25 at the entrance endof the passage, that is at the end nearest in succession to the inletpassage 28. Such a valve may have a stem 44 which reciprocates looselyin a passage 45 in the top wall of the box or element 24, the valve stemcarrying a valve head 46 upon its outer end which is adapted to seat bygravity against the upper face of the box 24 when the valve stem isallowed to drop and carry the lower valve head 43 downwardly in thechamber 25 and open communication through the particular passage 26which it controls. Such a valve is shown in Fig. 8 in the position inwhich it establishes communication through the passage 26 which itcontrols, the passage or opening 45 being closed by the outer valve head48 when the passage 26 under control is open. It will be obvious,however, that when the valve head 43 is shifted to close its passage 26,the passage 26 beyond the valve will be opened to atmos phere throughthe passage 45, owing to the upward movement of the head 46. thiscondition of the valve being shown in Fig. 9.

From the foregoing it will be observed that each chamber 25 of thecontrol box or element 24 is separately and individually connected by aconduit 41 to an individual secondary sound producing device, wheneverthe valve rod 37 entering that chamber is shifted into the positionshown in Fig. 9. It will be further observed that communication betweenthat chamber 25 and the next chamher in succession will be closed whenthe valve 43 in that chamber is shift-ed upwardly to closed position, asshown in Fig. 9, the remaining chambers in succession away from thefirst end chamber to which the passage 29 communicates, being vented toatmosphere through the passage 45, as shown in Fig. 9.

The control box or element 24 is also provided (Figs. 6, 8 and 9) with aplurality of passages 47, one for each chamber 25., and each passage 47has three branch openings 48, 49 and leading to its chamber A flexiblediaphragm 51 may be secured over each of the passages 48 and 49 to closethe same and be capable of a limited movement in and out of the opening,such as. between the positions shown in Figs. 8 and 9-. The passage 50may also be closed by a diaphragm 51 but the portion of the diaphragmover this passage 50 is provided with a small bleed port 52. Wheneverany passage 47 is open to the atmosphere and the corresponding chamber25 has a partial vacuum therein, the atmospheric pressure in thatpassage 47 wi llcause an upward movement of the pouches formed by thediaphragms 51 over the openings 48 and 49-, as shown in Fig. 9. Thediaphragm 51 which is over the passage 48, acts upon a head 53 providedupon the lower end of the valve stem 37, so that the upward movement ofthis pouch or diaphragm 51 will cause a movement of the valve stem 37from the position shown in Fig. 8 to the position shown in Fig. 9, thusopening communication be tween that chamber 25 and its conduit 41. Theatmospheric pressure in the same passage 47 will at the same timeelevate the pouch formed by the diaphragm 51 over the passage 49, andthis pouch or diaphragm acts upon the head of the valve 43 which is inthat related chamber 25, so as to shift it from the open position shownin F 8 to the closed or cut off position shown in F 9. While some of theair of that passage 47, which is open to atmosphere will leak throughthe bleed port 52 into the chamber 25, the amount so leaking will not besufficient to break the vacuum in the chamber 25, the port 52 being madesmall enough to prevent that happening. Thus, when any passage 47 isopen to atmosphere, the partial vacuum in its related chamber 25 willimmediately cause an operation of the valve stems 37 and 44 bydiaphragms 51 to connect that chamber with its secondary sound-producingdevice through the conduit 41, and to shut off communication betweenthat chamber and the chambers neXt in succession from the main inletpassage 28, the chambers 25 thus shut off being vented to the atmosphereto break the vacuum therein.

Each passage 47 is connected by a tube 54 to an individual port 55 in acontrol device 56. The individual ports 55 are closed by individualvalves 57, and each valve 57 is normally biased to closed position butdisposed for operation to open position by an arm 58 on a link 11a, sothat whenever any individual primary sound-producing instrumentality isoperated, it will operate one of the valves 57 to open the port and thusvent the related tube 54 to atmosphere. The

bleed port 52 leading to each passage 47 will serve to cause a partialvacuum in each passage 47, whenever the port communicating therewith isclosed. However, when the port communicating therewithis opened orvented to atmosphere, the partial vacuum in the passage l7. will bebroken and the atmospheric air pressure thereupon created therein willcause operation of the valves of that related chamber 25, as shown inFig. 9.

From the foregoing it will be observed that the secondarysound-producingdevices will be operated concomitantly and individuallyby the related primary sound producing instrumentalities, and theformerwill produce sounds of related musical pitch, but of differenttimbre than those produced concomitantly by the operation of the primarysound producing instrumentalities. however, are often operated ingroups, that is, a plurality may be operated at a time, and it isusually undesirable to have more than one secondary sound-producingdevice operating while any group of primary instrumentalities areoperating. 7

' If it be assumed that a plurality or group of primaryinstrumentalities, such as a plurality'of keys 10, are operated atonetime, a plurality of ports 55 will be vented to at inosphere at the sametime, and therefore atmospheric conditions will be createdsimultaneously in a plurality of passages 47. This will tend to operatethe valve rods 37 and 44 of each of the related chambers 25, but theresulting closing operation of the valve head 43 in the chamber 25 whichis nearest the inlet passage 28 through which suction is communicated tothe chambers, will promptly shut off the suction to the other chambersfarther from the inlet passage 28, and will vent those other shut offchambers 25 to atmosphere. Vhen the shut off chambers 25 are atatmospheric pressure, there can be no operation of the secondary-sound-producing devices which they control, because the air pressurewill be balanced upon both faces of the diaphragms 51 in those chambersand thus there will be no operating force on any of the valve stems 37.

l/Vhen the'inlet passage'28 is connected first to the end chamber 25which controls the sound producing-device causing the highest note ofthe scale portion covered bythe sec ondary sound-producing devices, itwill be obvious that only the instrumentality creating the highest noteof any group played at any time Will be effective to cause an operationof a related secondary sound-producing device. Thus if the keys 10 areplayed in groups, at one time, the secondary sound producin devices willoperate to play, for example, the highest note corresponding to thehighest note of the group being played. This is sometimes calledcarrying the air, and

V a the secondary notes, that is, those produced The latter,

by the secondary sound producing devices will carry the airf of theselection being played in addition to the regular notes, but secondarynotes. preferably differ in timbre from those produced by the primaryinstrumentalities or are one or more octaves differ ent in pitchtherefrom. On the other hand, if the inlet passage 28 should beconnected to the other end of the casing, it will be understood that thesecondary sound-producing v devices would play notes corresponding tothe ing the valve 29 inwarc ly, a handle 59 being provided to facilitatesuch operation of the c valve. Obviously, difierent similar sets ofsecondary sound-producing devices, differing in timbre from one anothermaybe connected in parallel to one another under the control of thelinks 11a or primary instrumentalities, and thus the air of anyselection may be carried by one or more of the secondary devices merelyby operating the valves 29 which control the connections of the suctionpipe 20 to the particular secondary devices which one desires toutilize. This duplication of secondary devices is, how-' ever, largelyomitted from this'disclosure, in the interest of clarity andto avoidconfusion as to the basic principle of the invention. Therefore,portions only of duplicate elements 24, 42 and 56 are shown at the rightof Fig. 2, V r

The operation of the device is believed to be clear from the foregoingdescription, but

will be briefly summarized. T o render the secondary-so-undproducingdevice eifective, theoperator pulls the handle 59 outwardly and thus byopening the valve 29 connects the suction pipe 20 to the control boX orelement 24. The operator then either plays a selection by operating thekeys 10 as usual in the'playing of a selection upon a piano, or

ated, a valve 57 will be operated thereby to vent a port 55, and theventing of that port will vent a passage 47 in the control box and thuscause the actuation of a related secondary sound-producing device.

lll)

IV in:

When the valve 57 is released at the stop- 7' .of those of the firstset, and for the concomitant operation of all theother of saidinstrumentalities of. the said second set.

ping of the primary instrumentality, it will close its port 5.5 .andthus close the passage 47. The bleed port 52 enables a prompt automaticbalancing of the partial vacuum pressures on-both sides of thediaphragms 51 when the port 55 is closed following a stopping of asecondary sound-producing device.

When the improvements specified are applied to automatically operatedmusical instruments, the effects produced by my im provements can beobtained by using the usual note sheets heretofore employed, nospecially cut or perforated sheets being necessary.

If reference is had to Figs. 1 and 2, it will be noted :that the variouselements of the secondary sound-producingdevice are arranged in rear ofand below the keyaction 11, pneumatic hammer operating means, and thekey board, so that these latter instrumentalities can be adjusted,repaired, or inserted, or removed from the instrument in the usualmanner, without in any way disturbing the secondary devices, which afterbeing once installed can remain permanently in place.

It willbe obvious that various changes in the details which have beenherein described and illustrated in order to explain the nature of theinvention, may be madeby those skilled in the art within the principleand scope of the .invention as expressed .in the appended claims.

for producing a series of notes of the musical scale in any desiredsequence, a second set of instrumentalities for producing musical :notescovering a selected musical range but differing in timbre fromthose ofthe first set, and means controlled by the instrumentalities of'thefirst set .forcausing operation of one instrumenta'lity of the secondset concomitantly with any group of one onmore preventing 2. In amusical'instrument, .a set ofseparate, selectively operableinstrumentalities for producing .a series of notes of the musical scalein any desired sequence and-in any desired groups, a-second setof'instrumentali- -1E18Sjf0l producing musical-notes covering a selectedmusi-calran-gebut differing in timbre fromthose of the first set, andmeans controlled 'by the instrumentalities of thefirst set for operatingthe instrumentalities ofrthe second set concomitantly and in a relativemusicalsequence withthe operation of the end'instrumentality of eachsimultaneously played group of the first set.

3. Ina musical instrument, a set of separate, selectively operableinstrumentalities for producing a series of notes of the musical scalein any desired sequence a series of individuall-y operable devices forproducing musical notes covering a selected musical range but differingin timbre from the said series of notes, and means including anindividual connection between each of said instrumentalities and anindividual device which produces a note having a desired harmoniousrelation on the musical scale to the note produced by thati-nstrumentality, whereby when each instrumentality is operated toproduce one note, its related device will also be operated to produce anote having a desired musical relation to said one note, and meansoperable automatically, when a group of said instrumentalities areoperated at one time, for permitting operation of that device which isrelated to one of the end instrumentalities of said group, andpreventing concomitant operation of all the other devices.

4. In a musical instrument, a set of separate selectively operableinstrumentalities for producing a series of notes ofthe musical scale inany desired sequence, a seriesof-individually operable devices forproducing musical notes covering a selected musical range but differentin t'mbre from said series of notes, individual pneumatic means con,-trolling the operation of each of said devices,

crating each pneumatic means and connected 5 to saidindividual pneumaticmeans-in series, and controlling means for individuallycontrollingcommunication between any two of said pneumatic means inseries,- each individual controlling means bein in turn controlledindividually by one ofsaid instrumentalities, and when renderedeffective at any actuation, operative to cut off said source from allindividual means farther along in said series of connections whereby ateach operation of an instrumentality, a device will be operated toproduce a note having a desired musical relation to the note-of theinstrumentality causing its operation, and operation of the otherdevices controlled .by .the individual means farther along in saidseries of connections prevented.

5. In a musical instrument, aset of separate selectively operableinstrumentalities ,for producing a series of notes ofthe musical scalein any desired sequence, a series of individually operable devices forproducing musical notes covering a selected musical range but differentin timbre fromsaid series of notes, individual pneumatic meanscontrolling the operation of each of said devices,

a common pneumatic source of power for operating each pneumatic means,a: plurality of pneiunatic elements operable individually by saidinstrumentalities for controlling individually the communication betweensaid common pneumatic sourceof power andsaid pneumatic means, wherebywhen each instru- 'mentality is operated to produce one note,

one of said devices will be also operated to produce a note having adesired musical relation to said one note, and said elements beingadapted whenever a group of said instrumentalities are operated at onetime, to permit operation or that device which is related to one of theend instrumentalities of said group and prevent concomitant operation ofall the other of said otherwise be operated by that group.

6; In a musical instrument, a control element having a plurality ofseparate chambers communicating with one another in succession, achamber control valve controlling the communication between each pair ofchambers, means for creating a partial vacuum in one of the endchambers, and through it successively in the other chambers, a pluralityof sound-producing devices, means including a separate conduitcontrolling each device independently of the others and operable uponthe creation of a partial vacuum in said conduit to cause operation ofsaid device, each conduit being connected to one of the chambers forindividual control thereby, a vent valve separately controllingcommunication of each conduit to its chamber and when preventing suchcommunication, serving to vent its conduit to break any vacuum therein,and means for operating the vent valves leading to said chambers topermit communication of each chamber with its conduit selectively in anysequence and concomitantly operating the valve preventing communicationof any chamber which may be connected to its conduit by its vent valve,

with the chambers beyond it from said one end chamber, whereby but onedevice may be operated at a time.

7. In a musical instrument, a set of separate, selectively operableinstrumentalities for producing a series of notes of the musical scalein any desired sequence, a series of individually operable devices forproducing notes covering a selected musical range but differing intimbre from said series of notes, a control element having a pluralityotseparate chambers communicating with one another in succession,a'conduit connecting each of said chambers with one of said devices, a

valve controlling communication between each conduit and its chamber,means connected to one of the end chambers of said element for creatingtherein a pneumatic pressure below atmosphere and communicating thatpressure to the other chambers in succession, individual valvescontrolling communication between successive chambers, and individualmeans controlled by each instrumentality and in turn controlling thevalves of a related chamber that in turn control the communication ofthat chamber with its conduit and with the chamber neXt in successionthereto, whereby at the operation of each instrumentality the relatedvalves in one of 1 said chambers will be operated to connect the deviceswhich would chamber with its. conduit and thereby cause operation of arelated device, and also automatically cut oii all other chambers ot'theseries farther along in the succession to prevent operation of thedevices controlled by the chambers which are cut ofli.

8., In a musical instrument, a set of separately operableinstrumentalities for producing a series of notes of the musical scalein any desired sequence, a series of individually operable devices forproducing musical notes coveringa selected musical range but diileringin timbre from said series of notes, means including an' individualpneumatic conduit controlling each device, a source of pneumatic powerconnected to said means in series to one another, means including valvesleading to each conduit and connected to said source of power forindividually connecting said source to said conduit pneumatically, andcutting oii from said source all other means farther along in itsseries, and means for controlling said valves individually, in turnindividually con rolled by said instrumentalities, whereby at theoperation of each instrumentality, or concomitantly of a group thereof,one only of said devices will be concomitantly operated to produce anote having a desired musical relation, and that device operated withone note of the actuated instrumentality.

9. In a musical instrument, a set ofseparately operableinstrumentalities for producing a series of notes of the musical scalein any desired sequence, a series of individually operable devices forproducing musical notes covering a selected musical range but differingin timbre from said series of notes, means including an individualpneumatic conduit controlling each device, a source of pneumatic power,means including valves leading to each conduit and connectedto saidsource of power for individually connecting said source to said conduitpneumatically, means "for controllin said valves individually,

in'turn individually controlled by said instrumentalities, whereby atthe operation of each instrumentality, one of said devices will beoperated to produce a note having a desired musical relation to the'noteof the actuated instrumentality, and means operable automatically toprevent the concomitant operation of more than one of said devices.

10. In a musical instrument, a casing having a plurality of separatechambers communicating with one another in succession, a

plurality of pneumatically controlled soundproducing devices, a controlconduit connecting each chamber with one of said devices, a valvecontrolling communication of each conduit and its chamber, a source ofpneumatic power connected to one of the end chambers which are connectedin succession and through it to the other chambers, individual valvescontrolling communication between successive chambers, means jointlycontrolling the valve leading to each conduit and the valve of the samechamber communicating with the chamber next in succession thereto fromthe said one end chamber, means for operating said last named meansindividually and in groups, the valves controlling communication betweensaid chambers automatically cutting off said source of power from allchambers in succession beyond the first chamber nearest said onechamber, which may be connected at any time to its conduit.

11. In a musical instrument, a plurality of sound-producing devices, acontrol box therefor having a plurality of chambers arranged in a row,said box having individual passages connecting said chambers to oneanother in succession and having a suction connection to one of the endchambers, a valve 0 controlling each individual passage and having anoperating part disposed in the chamher at the inlet end of that passage,an individual conduit leading from each chamber to one of the soundproducing devices, a valve controlling the communication of each conduitwith its chamber and having an operating part in said chamber, said boxalso having a plurality of control passages, one adj acent each chamberwhich it controls, and each opening into its chamber at a plurality ofpoints, one of said points of openings being a bleed port having a smallaperture, and means associated with the other opening points foroperating the valves by atmospheric pressure in that control passage,and

means for selectively and individually venting said control passages toatmosphere, whereby whenever a control passage is vented to atmosphere,the air pressure therein acting against the partial vacuum causedsuccessively by the suction in said chambers will operate the valves ofthe related chamber and connect the suction in that chamber to itsconduit and close the individual passage from that chamber to the otherchambers next in succession therefrom in order that suction may becommunicated to but one of said conduits at a time, said bleed portautomatically causing a restoration of a partial vacuum in each controlpassage whenever that passage is closed to atmosphere.

In testimony to the foregoing I hereto sign my name.

SELVIYOR A. SWANSON.

